Study on Spatial and Temporal Characteristics of Terrestrial Vegetation Carbon Sink in Liaoning Province

“Carbon neutrality” has become an important goal in China. Terrestrial vegetation carbon sink is a process of natural carbon absorption and an effective way to achieve carbon neutrality. The net primary productivity (NPP) of vegetation can be used as an index to measure the vegetation carbon sink. In this paper, the NPP of land vegetation in Liaoning Province from 2001 to 2020 is simulated by Carnegie-Ames-Stanford Approach (CASA) model, and the data is verified with MODIS NPP products, other research results and measured data. The inter-annual, seasonal and spatial variations of NPP are analyzed by using simple linear regression. The results show that the average NPP showed a slow rising trend, and the mean NPP in 20 years is 640.5 gC/m2/a. The rapid accumulation period of NPP from May to September is about 86.0% of the annual total. In terms of space, affected by the combination of water and heat, there is a decreasing trend from the east and west to the middle, with half of the areas showing an increasing trend, and the change slope is concentrated in the range of 0–10 gC/m2/a. In half of the areas, NPP decreases, mainly around the city, which is caused by the destruction of vegetation caused by urbanization.